Initially, only a small group of businesses will have access to this new advertising opportunity -- Twitter wouldn't say how many, although a spokesman allowed that the number of participating small businesses will "steadily increase" in coming weeks. If it works as advertised --no pun intended --this could be a very big deal for the company, one that could allow it to tap into a huge new swathe of potential advertisers.

The hope within Twitter is that the new program could have the same sort of impact on Twitter's business that AdWords had for Google.

That's a tall order -- but at least Twitter's finally out of the gate. In February, Twitter announced plans to let small businesses to set up advertising accounts on their own. Those would allow them to highlight promotions and messages in their customers' Twitter timelines, among other things.

The program offers would-be advertisers two options:

Promoted accounts: Twitter will analyze the current followers of a small business and then search for other Twitter users with similar interests. Twitter will then promote the company to those people through its "Who to Follow" box on the site.

Promoted tweets: Twitter constantly monitors a small businesses' tweets and then automatically promotes the "best" -- presumably the stickiest -- of those across its site. These "aren't like traditional ads," the company says in a promotional video, because no one is writing ad copy -- Twitter is merely expanding the reach of tweets a business is already putting out.

Twitter will only charge businesses when someone follows its account or engages with a promoted tweet. A spokesman declined to elaborate on the financial arrangements. In its video, the company says this:

You determine the limit of how much you want to spend per day and how much you want to spend per new follower or engagement, so there are never any surprises. You can also decide where geographically where you want your content to be promoted.